net/ipv4/ip_output.c

   1 /*
   2  * INET         An implementation of the TCP/IP protocol suite for the LINUX
   3  *              operating system.  INET is implemented using the  BSD Socket
   4  *              interface as the means of communication with the user level.
   5  *
   6  *              The Internet Protocol (IP) output module.
   7  *
   8  * Authors:     Ross Biro
   9  *              Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
  10  *              Donald Becker, <becker@super.org>
  11  *              Alan Cox, <Alan.Cox@linux.org>
  12  *              Richard Underwood
  13  *              Stefan Becker, <stefanb@yello.ping.de>
  14  *              Jorge Cwik, <jorge@laser.satlink.net>
  15  *              Arnt Gulbrandsen, <agulbra@nvg.unit.no>
  16  *              Hirokazu Takahashi, <taka@valinux.co.jp>
  17  *
  18  *      See ip_input.c for original log
  19  *
  20  *      Fixes:
  21  *              Alan Cox        :       Missing nonblock feature in ip_build_xmit.
  22  *              Mike Kilburn    :       htons() missing in ip_build_xmit.
  23  *              Bradford Johnson:       Fix faulty handling of some frames when
  24  *                                      no route is found.
  25  *              Alexander Demenshin:    Missing sk/skb free in ip_queue_xmit
  26  *                                      (in case if packet not accepted by
  27  *                                      output firewall rules)
  28  *              Mike McLagan    :       Routing by source
  29  *              Alexey Kuznetsov:       use new route cache
  30  *              Andi Kleen:             Fix broken PMTU recovery and remove
  31  *                                      some redundant tests.
  32  *      Vitaly E. Lavrov        :       Transparent proxy revived after year coma.
  33  *              Andi Kleen      :       Replace ip_reply with ip_send_reply.
  34  *              Andi Kleen      :       Split fast and slow ip_build_xmit path
  35  *                                      for decreased register pressure on x86
  36  *                                      and more readibility.
  37  *              Marc Boucher    :       When call_out_firewall returns FW_QUEUE,
  38  *                                      silently drop skb instead of failing with -EPERM.
  39  *              Detlev Wengorz  :       Copy protocol for fragments.
  40  *              Hirokazu Takahashi:     HW checksumming for outgoing UDP
  41  *                                      datagrams.
  42  *              Hirokazu Takahashi:     sendfile() on UDP works now.
  43  */
  44
  45 #include <asm/uaccess.h>
  46 #include <asm/system.h>
  47 #include <linux/module.h>
  48 #include <linux/types.h>
  49 #include <linux/kernel.h>
  50 #include <linux/mm.h>
  51 #include <linux/string.h>
  52 #include <linux/errno.h>
  53 #include <linux/highmem.h>
  54 #include <linux/slab.h>
  55
  56 #include <linux/socket.h>
  57 #include <linux/sockios.h>
  58 #include <linux/in.h>
  59 #include <linux/inet.h>
  60 #include <linux/netdevice.h>
  61 #include <linux/etherdevice.h>
  62 #include <linux/proc_fs.h>
  63 #include <linux/stat.h>
  64 #include <linux/init.h>
  65
  66 #include <net/snmp.h>
  67 #include <net/ip.h>
  68 #include <net/protocol.h>
  69 #include <net/route.h>
  70 #include <net/xfrm.h>
  71 #include <linux/skbuff.h>
  72 #include <net/sock.h>
  73 #include <net/arp.h>
  74 #include <net/icmp.h>
  75 #include <net/checksum.h>
  76 #include <net/inetpeer.h>
  77 #include <linux/igmp.h>
  78 #include <linux/netfilter_ipv4.h>
  79 #include <linux/netfilter_bridge.h>
  80 #include <linux/mroute.h>
  81 #include <linux/netlink.h>
  82 #include <linux/tcp.h>
  83
  84 int sysctl_ip_default_ttl __read_mostly = IPDEFTTL;
  85 EXPORT_SYMBOL(sysctl_ip_default_ttl);
  86
  87 /* Generate a checksum for an outgoing IP datagram. */
  88 __inline__ void ip_send_check(struct iphdr *iph)
  89 {
  90         iph->check = 0;
  91         iph->check = ip_fast_csum((unsigned char *)iph, iph->ihl);
  92 }
  93 EXPORT_SYMBOL(ip_send_check);
  94
  95 int __ip_local_out(struct sk_buff *skb)
  96 {
  97         struct iphdr *iph = ip_hdr(skb);
  98
  99         iph->tot_len = htons(skb->len);
 100         ip_send_check(iph);
 101         return nf_hook(NFPROTO_IPV4, NF_INET_LOCAL_OUT, skb, NULL,
 102                        skb_dst(skb)->dev, dst_output);
 103 }
 104
 105 int ip_local_out(struct sk_buff *skb)
 106 {
 107         int err;
 108
 109         err = __ip_local_out(skb);
 110         if (likely(err == 1))
 111                 err = dst_output(skb);
 112
 113         return err;
 114 }
 115 EXPORT_SYMBOL_GPL(ip_local_out);
 116
 117 /* dev_loopback_xmit for use with netfilter. */
 118 static int ip_dev_loopback_xmit(struct sk_buff *newskb)
 119 {
 120         skb_reset_mac_header(newskb);
 121         __skb_pull(newskb, skb_network_offset(newskb));
 122         newskb->pkt_type = PACKET_LOOPBACK;
 123         newskb->ip_summed = CHECKSUM_UNNECESSARY;
 124         WARN_ON(!skb_dst(newskb));
 125         netif_rx_ni(newskb);
 126         return 0;
 127 }
 128
 129 static inline int ip_select_ttl(struct inet_sock *inet, struct dst_entry *dst)
 130 {
 131         int ttl = inet->uc_ttl;
 132
 133         if (ttl < 0)
 134                 ttl = ip4_dst_hoplimit(dst);
 135         return ttl;
 136 }
 137
 138 /*
 139  *              Add an ip header to a skbuff and send it out.
 140  *
 141  */
 142 int ip_build_and_send_pkt(struct sk_buff *skb, struct sock *sk,
 143                           __be32 saddr, __be32 daddr, struct ip_options_rcu *opt)
 144 {
 145         struct inet_sock *inet = inet_sk(sk);
 146         struct rtable *rt = skb_rtable(skb);
 147         struct iphdr *iph;
 148
 149         /* Build the IP header. */
 150         skb_push(skb, sizeof(struct iphdr) + (opt ? opt->opt.optlen : 0));
 151         skb_reset_network_header(skb);
 152         iph = ip_hdr(skb);
 153         iph->version  = 4;
 154         iph->ihl      = 5;
 155         iph->tos      = inet->tos;
 156         if (ip_dont_fragment(sk, &rt->dst))
 157                 iph->frag_off = htons(IP_DF);
 158         else
 159                 iph->frag_off = 0;
 160         iph->ttl      = ip_select_ttl(inet, &rt->dst);
 161         iph->daddr    = (opt && opt->opt.srr ? opt->opt.faddr : daddr);
 162         iph->saddr    = saddr;
 163         iph->protocol = sk->sk_protocol;
 164         ip_select_ident(iph, &rt->dst, sk);
 165
 166         if (opt && opt->opt.optlen) {
 167                 iph->ihl += opt->opt.optlen>>2;
 168                 ip_options_build(skb, &opt->opt, daddr, rt, 0);
 169         }
 170
 171         skb->priority = sk->sk_priority;
 172         skb->mark = sk->sk_mark;
 173
 174         /* Send it out. */
 175         return ip_local_out(skb);
 176 }
 177 EXPORT_SYMBOL_GPL(ip_build_and_send_pkt);
 178
 179 static inline int ip_finish_output2(struct sk_buff *skb)
 180 {
 181         struct dst_entry *dst = skb_dst(skb);
 182         struct rtable *rt = (struct rtable *)dst;
 183         struct net_device *dev = dst->dev;
 184         unsigned int hh_len = LL_RESERVED_SPACE(dev);
 185         struct neighbour *neigh;
 186
 187         if (rt->rt_type == RTN_MULTICAST) {
 188                 IP_UPD_PO_STATS(dev_net(dev), IPSTATS_MIB_OUTMCAST, skb->len);
 189         } else if (rt->rt_type == RTN_BROADCAST)
 190                 IP_UPD_PO_STATS(dev_net(dev), IPSTATS_MIB_OUTBCAST, skb->len);
 191
 192         /* Be paranoid, rather than too clever. */
 193         if (unlikely(skb_headroom(skb) < hh_len && dev->header_ops)) {
 194                 struct sk_buff *skb2;
 195
 196                 skb2 = skb_realloc_headroom(skb, LL_RESERVED_SPACE(dev));
 197                 if (skb2 == NULL) {
 198                         kfree_skb(skb);
 199                         return -ENOMEM;
 200                 }
 201                 if (skb->sk)
 202                         skb_set_owner_w(skb2, skb->sk);
 203                 kfree_skb(skb);
 204                 skb = skb2;
 205         }
 206
 207         neigh = dst->neighbour;
 208         if (neigh) {
 209                 struct hh_cache *hh = &neigh->hh;
 210                 if (hh->hh_len)
 211                         return neigh_hh_output(hh, skb);
 212                 else
 213                         return dst->neighbour->output(skb);
 214         }
 215         if (net_ratelimit())
 216                 printk(KERN_DEBUG "ip_finish_output2: No header cache and no neighbour!\n");
 217         kfree_skb(skb);
 218         return -EINVAL;
 219 }
 220
 221 static inline int ip_skb_dst_mtu(struct sk_buff *skb)
 222 {
 223         struct inet_sock *inet = skb->sk ? inet_sk(skb->sk) : NULL;
 224
 225         return (inet && inet->pmtudisc == IP_PMTUDISC_PROBE) ?
 226                skb_dst(skb)->dev->mtu : dst_mtu(skb_dst(skb));
 227 }
 228
 229 static int ip_finish_output(struct sk_buff *skb)
 230 {
 231 #if defined(CONFIG_NETFILTER) && defined(CONFIG_XFRM)
 232         /* Policy lookup after SNAT yielded a new policy */
 233         if (skb_dst(skb)->xfrm != NULL) {
 234                 IPCB(skb)->flags |= IPSKB_REROUTED;
 235                 return dst_output(skb);
 236         }
 237 #endif
 238         if (skb->len > ip_skb_dst_mtu(skb) && !skb_is_gso(skb))
 239                 return ip_fragment(skb, ip_finish_output2);
 240         else
 241                 return ip_finish_output2(skb);
 242 }
 243
 244 int ip_mc_output(struct sk_buff *skb)
 245 {
 246         struct sock *sk = skb->sk;
 247         struct rtable *rt = skb_rtable(skb);
 248         struct net_device *dev = rt->dst.dev;
 249
 250         /*
 251          *      If the indicated interface is up and running, send the packet.
 252          */
 253         IP_UPD_PO_STATS(dev_net(dev), IPSTATS_MIB_OUT, skb->len);
 254
 255         skb->dev = dev;
 256         skb->protocol = htons(ETH_P_IP);
 257
 258         /*
 259          *      Multicasts are looped back for other local users
 260          */
 261
 262         if (rt->rt_flags&RTCF_MULTICAST) {
 263                 if (sk_mc_loop(sk)
 264 #ifdef CONFIG_IP_MROUTE
 265                 /* Small optimization: do not loopback not local frames,
 266                    which returned after forwarding; they will be  dropped
 267                    by ip_mr_input in any case.
 268                    Note, that local frames are looped back to be delivered
 269                    to local recipients.
 270
 271                    This check is duplicated in ip_mr_input at the moment.
 272                  */
 273                     &&
 274                     ((rt->rt_flags & RTCF_LOCAL) ||
 275                      !(IPCB(skb)->flags & IPSKB_FORWARDED))
 276 #endif
 277                    ) {
 278                         struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC);
 279                         if (newskb)
 280                                 NF_HOOK(NFPROTO_IPV4, NF_INET_POST_ROUTING,
 281                                         newskb, NULL, newskb->dev,
 282                                         ip_dev_loopback_xmit);
 283                 }
 284
 285                 /* Multicasts with ttl 0 must not go beyond the host */
 286
 287                 if (ip_hdr(skb)->ttl == 0) {
 288                         kfree_skb(skb);
 289                         return 0;
 290                 }
 291         }
 292
 293         if (rt->rt_flags&RTCF_BROADCAST) {
 294                 struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC);
 295                 if (newskb)
 296                         NF_HOOK(NFPROTO_IPV4, NF_INET_POST_ROUTING, newskb,
 297                                 NULL, newskb->dev, ip_dev_loopback_xmit);
 298         }
 299
 300         return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING, skb, NULL,
 301                             skb->dev, ip_finish_output,
 302                             !(IPCB(skb)->flags & IPSKB_REROUTED));
 303 }
 304
 305 int ip_output(struct sk_buff *skb)
 306 {
 307         struct net_device *dev = skb_dst(skb)->dev;
 308
 309         IP_UPD_PO_STATS(dev_net(dev), IPSTATS_MIB_OUT, skb->len);
 310
 311         skb->dev = dev;
 312         skb->protocol = htons(ETH_P_IP);
 313
 314         return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING, skb, NULL, dev,
 315                             ip_finish_output,
 316                             !(IPCB(skb)->flags & IPSKB_REROUTED));
 317 }
 318
 319 int ip_queue_xmit(struct sk_buff *skb, struct flowi *fl)
 320 {
 321         struct sock *sk = skb->sk;
 322         struct inet_sock *inet = inet_sk(sk);
 323         struct ip_options_rcu *inet_opt;
 324         struct flowi4 *fl4;
 325         struct rtable *rt;
 326         struct iphdr *iph;
 327         int res;
 328
 329         /* Skip all of this if the packet is already routed,
 330          * f.e. by something like SCTP.
 331          */
 332         rcu_read_lock();
 333         inet_opt = rcu_dereference(inet->inet_opt);
 334         fl4 = &fl->u.ip4;
 335         rt = skb_rtable(skb);
 336         if (rt != NULL)
 337                 goto packet_routed;
 338
 339         /* Make sure we can route this packet. */
 340         rt = (struct rtable *)__sk_dst_check(sk, 0);
 341         if (rt == NULL) {
 342                 __be32 daddr;
 343
 344                 /* Use correct destination address if we have options. */
 345                 daddr = inet->inet_daddr;
 346                 if (inet_opt && inet_opt->opt.srr)
 347                         daddr = inet_opt->opt.faddr;
 348
 349                 /* If this fails, retransmit mechanism of transport layer will
 350                  * keep trying until route appears or the connection times
 351                  * itself out.
 352                  */
 353                 rt = ip_route_output_ports(sock_net(sk), fl4, sk,
 354                                            daddr, inet->inet_saddr,
 355                                            inet->inet_dport,
 356                                            inet->inet_sport,
 357                                            sk->sk_protocol,
 358                                            RT_CONN_FLAGS(sk),
 359                                            sk->sk_bound_dev_if);
 360                 if (IS_ERR(rt))
 361                         goto no_route;
 362                 sk_setup_caps(sk, &rt->dst);
 363         }
 364         skb_dst_set_noref(skb, &rt->dst);
 365
 366 packet_routed:
 367         if (inet_opt && inet_opt->opt.is_strictroute && fl4->daddr != rt->rt_gateway)
 368                 goto no_route;
 369
 370         /* OK, we know where to send it, allocate and build IP header. */
 371         skb_push(skb, sizeof(struct iphdr) + (inet_opt ? inet_opt->opt.optlen : 0));
 372         skb_reset_network_header(skb);
 373         iph = ip_hdr(skb);
 374         *((__be16 *)iph) = htons((4 << 12) | (5 << 8) | (inet->tos & 0xff));
 375         if (ip_dont_fragment(sk, &rt->dst) && !skb->local_df)
 376                 iph->frag_off = htons(IP_DF);
 377         else
 378                 iph->frag_off = 0;
 379         iph->ttl      = ip_select_ttl(inet, &rt->dst);
 380         iph->protocol = sk->sk_protocol;
 381         iph->saddr    = fl4->saddr;
 382         iph->daddr    = fl4->daddr;
 383         /* Transport layer set skb->h.foo itself. */
 384
 385         if (inet_opt && inet_opt->opt.optlen) {
 386                 iph->ihl += inet_opt->opt.optlen >> 2;
 387                 ip_options_build(skb, &inet_opt->opt, inet->inet_daddr, rt, 0);
 388         }
 389
 390         ip_select_ident_more(iph, &rt->dst, sk,
 391                              (skb_shinfo(skb)->gso_segs ?: 1) - 1);
 392
 393         skb->priority = sk->sk_priority;
 394         skb->mark = sk->sk_mark;
 395
 396         res = ip_local_out(skb);
 397         rcu_read_unlock();
 398         return res;
 399
 400 no_route:
 401         rcu_read_unlock();
 402         IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTNOROUTES);
 403         kfree_skb(skb);
 404         return -EHOSTUNREACH;
 405 }
 406 EXPORT_SYMBOL(ip_queue_xmit);
 407
 408
 409 static void ip_copy_metadata(struct sk_buff *to, struct sk_buff *from)
 410 {
 411         to->pkt_type = from->pkt_type;
 412         to->priority = from->priority;
 413         to->protocol = from->protocol;
 414         skb_dst_drop(to);
 415         skb_dst_copy(to, from);
 416         to->dev = from->dev;
 417         to->mark = from->mark;
 418
 419         /* Copy the flags to each fragment. */
 420         IPCB(to)->flags = IPCB(from)->flags;
 421
 422 #ifdef CONFIG_NET_SCHED
 423         to->tc_index = from->tc_index;
 424 #endif
 425         nf_copy(to, from);
 426 #if defined(CONFIG_NETFILTER_XT_TARGET_TRACE) || \
 427     defined(CONFIG_NETFILTER_XT_TARGET_TRACE_MODULE)
 428         to->nf_trace = from->nf_trace;
 429 #endif
 430 #if defined(CONFIG_IP_VS) || defined(CONFIG_IP_VS_MODULE)
 431         to->ipvs_property = from->ipvs_property;
 432 #endif
 433         skb_copy_secmark(to, from);
 434 }
 435
 436 /*
 437  *      This IP datagram is too large to be sent in one piece.  Break it up into
 438  *      smaller pieces (each of size equal to IP header plus
 439  *      a block of the data of the original IP data part) that will yet fit in a
 440  *      single device frame, and queue such a frame for sending.
 441  */
 442
 443 int ip_fragment(struct sk_buff *skb, int (*output)(struct sk_buff *))
 444 {
 445         struct iphdr *iph;
 446         int ptr;
 447         struct net_device *dev;
 448         struct sk_buff *skb2;
 449         unsigned int mtu, hlen, left, len, ll_rs;
 450         int offset;
 451         __be16 not_last_frag;
 452         struct rtable *rt = skb_rtable(skb);
 453         int err = 0;
 454
 455         dev = rt->dst.dev;
 456
 457         /*
 458          *      Point into the IP datagram header.
 459          */
 460
 461         iph = ip_hdr(skb);
 462
 463         if (unlikely((iph->frag_off & htons(IP_DF)) && !skb->local_df)) {
 464                 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS);
 465                 icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED,
 466                           htonl(ip_skb_dst_mtu(skb)));
 467                 kfree_skb(skb);
 468                 return -EMSGSIZE;
 469         }
 470
 471         /*
 472          *      Setup starting values.
 473          */
 474
 475         hlen = iph->ihl * 4;
 476         mtu = dst_mtu(&rt->dst) - hlen; /* Size of data space */
 477 #ifdef CONFIG_BRIDGE_NETFILTER
 478         if (skb->nf_bridge)
 479                 mtu -= nf_bridge_mtu_reduction(skb);
 480 #endif
 481         IPCB(skb)->flags |= IPSKB_FRAG_COMPLETE;
 482
 483         /* When frag_list is given, use it. First, check its validity:
 484          * some transformers could create wrong frag_list or break existing
 485          * one, it is not prohibited. In this case fall back to copying.
 486          *
 487          * LATER: this step can be merged to real generation of fragments,
 488          * we can switch to copy when see the first bad fragment.
 489          */
 490         if (skb_has_frag_list(skb)) {
 491                 struct sk_buff *frag, *frag2;
 492                 int first_len = skb_pagelen(skb);
 493
 494                 if (first_len - hlen > mtu ||
 495                     ((first_len - hlen) & 7) ||
 496                     ip_is_fragment(iph) ||
 497                     skb_cloned(skb))
 498                         goto slow_path;
 499
 500                 skb_walk_frags(skb, frag) {
 501                         /* Correct geometry. */
 502                         if (frag->len > mtu ||
 503                             ((frag->len & 7) && frag->next) ||
 504                             skb_headroom(frag) < hlen)
 505                                 goto slow_path_clean;
 506
 507                         /* Partially cloned skb? */
 508                         if (skb_shared(frag))
 509                                 goto slow_path_clean;
 510
 511                         BUG_ON(frag->sk);
 512                         if (skb->sk) {
 513                                 frag->sk = skb->sk;
 514                                 frag->destructor = sock_wfree;
 515                         }
 516                         skb->truesize -= frag->truesize;
 517                 }
 518
 519                 /* Everything is OK. Generate! */
 520
 521                 err = 0;
 522                 offset = 0;
 523                 frag = skb_shinfo(skb)->frag_list;
 524                 skb_frag_list_init(skb);
 525                 skb->data_len = first_len - skb_headlen(skb);
 526                 skb->len = first_len;
 527                 iph->tot_len = htons(first_len);
 528                 iph->frag_off = htons(IP_MF);
 529                 ip_send_check(iph);
 530
 531                 for (;;) {
 532                         /* Prepare header of the next frame,
 533                          * before previous one went down. */
 534                         if (frag) {
 535                                 frag->ip_summed = CHECKSUM_NONE;
 536                                 skb_reset_transport_header(frag);
 537                                 __skb_push(frag, hlen);
 538                                 skb_reset_network_header(frag);
 539                                 memcpy(skb_network_header(frag), iph, hlen);
 540                                 iph = ip_hdr(frag);
 541                                 iph->tot_len = htons(frag->len);
 542                                 ip_copy_metadata(frag, skb);
 543                                 if (offset == 0)
 544                                         ip_options_fragment(frag);
 545                                 offset += skb->len - hlen;
 546                                 iph->frag_off = htons(offset>>3);
 547                                 if (frag->next != NULL)
 548                                         iph->frag_off |= htons(IP_MF);
 549                                 /* Ready, complete checksum */
 550                                 ip_send_check(iph);
 551                         }
 552
 553                         err = output(skb);
 554
 555                         if (!err)
 556                                 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGCREATES);
 557                         if (err || !frag)
 558                                 break;
 559
 560                         skb = frag;
 561                         frag = skb->next;
 562                         skb->next = NULL;
 563                 }
 564
 565                 if (err == 0) {
 566                         IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGOKS);
 567                         return 0;
 568                 }
 569
 570                 while (frag) {
 571                         skb = frag->next;
 572                         kfree_skb(frag);
 573                         frag = skb;
 574                 }
 575                 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS);
 576                 return err;
 577
 578 slow_path_clean:
 579                 skb_walk_frags(skb, frag2) {
 580                         if (frag2 == frag)
 581                                 break;
 582                         frag2->sk = NULL;
 583                         frag2->destructor = NULL;
 584                         skb->truesize += frag2->truesize;
 585                 }
 586         }
 587
 588 slow_path:
 589         left = skb->len - hlen;         /* Space per frame */
 590         ptr = hlen;             /* Where to start from */
 591
 592         /* for bridged IP traffic encapsulated inside f.e. a vlan header,
 593          * we need to make room for the encapsulating header
 594          */
 595         ll_rs = LL_RESERVED_SPACE_EXTRA(rt->dst.dev, nf_bridge_pad(skb));
 596
 597         /*
 598          *      Fragment the datagram.
 599          */
 600
 601         offset = (ntohs(iph->frag_off) & IP_OFFSET) << 3;
 602         not_last_frag = iph->frag_off & htons(IP_MF);
 603
 604         /*
 605          *      Keep copying data until we run out.
 606          */
 607
 608         while (left > 0) {
 609                 len = left;
 610                 /* IF: it doesn't fit, use 'mtu' - the data space left */
 611                 if (len > mtu)
 612                         len = mtu;
 613                 /* IF: we are not sending up to and including the packet end
 614                    then align the next start on an eight byte boundary */
 615                 if (len < left) {
 616                         len &= ~7;
 617                 }
 618                 /*
 619                  *      Allocate buffer.
 620                  */
 621
 622                 if ((skb2 = alloc_skb(len+hlen+ll_rs, GFP_ATOMIC)) == NULL) {
 623                         NETDEBUG(KERN_INFO "IP: frag: no memory for new fragment!\n");
 624                         err = -ENOMEM;
 625                         goto fail;
 626                 }
 627
 628                 /*
 629                  *      Set up data on packet
 630                  */
 631
 632                 ip_copy_metadata(skb2, skb);
 633                 skb_reserve(skb2, ll_rs);
 634                 skb_put(skb2, len + hlen);
 635                 skb_reset_network_header(skb2);
 636                 skb2->transport_header = skb2->network_header + hlen;
 637
 638                 /*
 639                  *      Charge the memory for the fragment to any owner
 640                  *      it might possess
 641                  */
 642
 643                 if (skb->sk)
 644                         skb_set_owner_w(skb2, skb->sk);
 645
 646                 /*
 647                  *      Copy the packet header into the new buffer.
 648                  */
 649
 650                 skb_copy_from_linear_data(skb, skb_network_header(skb2), hlen);
 651
 652                 /*
 653                  *      Copy a block of the IP datagram.
 654                  */
 655                 if (skb_copy_bits(skb, ptr, skb_transport_header(skb2), len))
 656                         BUG();
 657                 left -= len;
 658
 659                 /*
 660                  *      Fill in the new header fields.
 661                  */
 662                 iph = ip_hdr(skb2);
 663                 iph->frag_off = htons((offset >> 3));
 664
 665                 /* ANK: dirty, but effective trick. Upgrade options only if
 666                  * the segment to be fragmented was THE FIRST (otherwise,
 667                  * options are already fixed) and make it ONCE
 668                  * on the initial skb, so that all the following fragments
 669                  * will inherit fixed options.
 670                  */
 671                 if (offset == 0)
 672                         ip_options_fragment(skb);
 673
 674                 /*
 675                  *      Added AC : If we are fragmenting a fragment that's not the
 676                  *                 last fragment then keep MF on each bit
 677                  */
 678                 if (left > 0 || not_last_frag)
 679                         iph->frag_off |= htons(IP_MF);
 680                 ptr += len;
 681                 offset += len;
 682
 683                 /*
 684                  *      Put this fragment into the sending queue.
 685                  */
 686                 iph->tot_len = htons(len + hlen);
 687
 688                 ip_send_check(iph);
 689
 690                 err = output(skb2);
 691                 if (err)
 692                         goto fail;
 693
 694                 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGCREATES);
 695         }
 696         kfree_skb(skb);
 697         IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGOKS);
 698         return err;
 699
 700 fail:
 701         kfree_skb(skb);
 702         IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS);
 703         return err;
 704 }
 705 EXPORT_SYMBOL(ip_fragment);
 706
 707 int
 708 ip_generic_getfrag(void *from, char *to, int offset, int len, int odd, struct sk_buff *skb)
 709 {
 710         struct iovec *iov = from;
 711
 712         if (skb->ip_summed == CHECKSUM_PARTIAL) {
 713                 if (memcpy_fromiovecend(to, iov, offset, len) < 0)
 714                         return -EFAULT;
 715         } else {
 716                 __wsum csum = 0;
 717                 if (csum_partial_copy_fromiovecend(to, iov, offset, len, &csum) < 0)
 718                         return -EFAULT;
 719                 skb->csum = csum_block_add(skb->csum, csum, odd);
 720         }
 721         return 0;
 722 }
 723 EXPORT_SYMBOL(ip_generic_getfrag);
 724
 725 static inline __wsum
 726 csum_page(struct page *page, int offset, int copy)
 727 {
 728         char *kaddr;
 729         __wsum csum;
 730         kaddr = kmap(page);
 731         csum = csum_partial(kaddr + offset, copy, 0);
 732         kunmap(page);
 733         return csum;
 734 }
 735
 736 static inline int ip_ufo_append_data(struct sock *sk,
 737                         struct sk_buff_head *queue,
 738                         int getfrag(void *from, char *to, int offset, int len,
 739                                int odd, struct sk_buff *skb),
 740                         void *from, int length, int hh_len, int fragheaderlen,
 741                         int transhdrlen, int mtu, unsigned int flags)
 742 {
 743         struct sk_buff *skb;
 744         int err;
 745
 746         /* There is support for UDP fragmentation offload by network
 747          * device, so create one single skb packet containing complete
 748          * udp datagram
 749          */
 750         if ((skb = skb_peek_tail(queue)) == NULL) {
 751                 skb = sock_alloc_send_skb(sk,
 752                         hh_len + fragheaderlen + transhdrlen + 20,
 753                         (flags & MSG_DONTWAIT), &err);
 754
 755                 if (skb == NULL)
 756                         return err;
 757
 758                 /* reserve space for Hardware header */
 759                 skb_reserve(skb, hh_len);
 760
 761                 /* create space for UDP/IP header */
 762                 skb_put(skb, fragheaderlen + transhdrlen);
 763
 764                 /* initialize network header pointer */
 765                 skb_reset_network_header(skb);
 766
 767                 /* initialize protocol header pointer */
 768                 skb->transport_header = skb->network_header + fragheaderlen;
 769
 770                 skb->ip_summed = CHECKSUM_PARTIAL;
 771                 skb->csum = 0;
 772
 773                 /* specify the length of each IP datagram fragment */
 774                 skb_shinfo(skb)->gso_size = mtu - fragheaderlen;
 775                 skb_shinfo(skb)->gso_type = SKB_GSO_UDP;
 776                 __skb_queue_tail(queue, skb);
 777         }
 778
 779         return skb_append_datato_frags(sk, skb, getfrag, from,
 780                                        (length - transhdrlen));
 781 }
 782
 783 static int __ip_append_data(struct sock *sk,
 784                             struct flowi4 *fl4,
 785                             struct sk_buff_head *queue,
 786                             struct inet_cork *cork,
 787                             int getfrag(void *from, char *to, int offset,
 788                                         int len, int odd, struct sk_buff *skb),
 789                             void *from, int length, int transhdrlen,
 790                             unsigned int flags)
 791 {
 792         struct inet_sock *inet = inet_sk(sk);
 793         struct sk_buff *skb;
 794
 795         struct ip_options *opt = cork->opt;
 796         int hh_len;
 797         int exthdrlen;
 798         int mtu;
 799         int copy;
 800         int err;
 801         int offset = 0;
 802         unsigned int maxfraglen, fragheaderlen;
 803         int csummode = CHECKSUM_NONE;
 804         struct rtable *rt = (struct rtable *)cork->dst;
 805
 806         skb = skb_peek_tail(queue);
 807
 808         exthdrlen = !skb ? rt->dst.header_len : 0;
 809         mtu = cork->fragsize;
 810
 811         hh_len = LL_RESERVED_SPACE(rt->dst.dev);
 812
 813         fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0);
 814         maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen;
 815
 816         if (cork->length + length > 0xFFFF - fragheaderlen) {
 817                 ip_local_error(sk, EMSGSIZE, fl4->daddr, inet->inet_dport,
 818                                mtu-exthdrlen);
 819                 return -EMSGSIZE;
 820         }
 821
 822         /*
 823          * transhdrlen > 0 means that this is the first fragment and we wish
 824          * it won't be fragmented in the future.
 825          */
 826         if (transhdrlen &&
 827             length + fragheaderlen <= mtu &&
 828             rt->dst.dev->features & NETIF_F_V4_CSUM &&
 829             !exthdrlen)
 830                 csummode = CHECKSUM_PARTIAL;
 831
 832         cork->length += length;
 833         if (((length > mtu) || (skb && skb_is_gso(skb))) &&
 834             (sk->sk_protocol == IPPROTO_UDP) &&
 835             (rt->dst.dev->features & NETIF_F_UFO) && !rt->dst.header_len) {
 836                 err = ip_ufo_append_data(sk, queue, getfrag, from, length,
 837                                          hh_len, fragheaderlen, transhdrlen,
 838                                          mtu, flags);
 839                 if (err)
 840                         goto error;
 841                 return 0;
 842         }
 843
 844         /* So, what's going on in the loop below?
 845          *
 846          * We use calculated fragment length to generate chained skb,
 847          * each of segments is IP fragment ready for sending to network after
 848          * adding appropriate IP header.
 849          */
 850
 851         if (!skb)
 852                 goto alloc_new_skb;
 853
 854         while (length > 0) {
 855                 /* Check if the remaining data fits into current packet. */
 856                 copy = mtu - skb->len;
 857                 if (copy < length)
 858                         copy = maxfraglen - skb->len;
 859                 if (copy <= 0) {
 860                         char *data;
 861                         unsigned int datalen;
 862                         unsigned int fraglen;
 863                         unsigned int fraggap;
 864                         unsigned int alloclen;
 865                         struct sk_buff *skb_prev;
 866 alloc_new_skb:
 867                         skb_prev = skb;
 868                         if (skb_prev)
 869                                 fraggap = skb_prev->len - maxfraglen;
 870                         else
 871                                 fraggap = 0;
 872
 873                         /*
 874                          * If remaining data exceeds the mtu,
 875                          * we know we need more fragment(s).
 876                          */
 877                         datalen = length + fraggap;
 878                         if (datalen > mtu - fragheaderlen)
 879                                 datalen = maxfraglen - fragheaderlen;
 880                         fraglen = datalen + fragheaderlen;
 881
 882                         if ((flags & MSG_MORE) &&
 883                             !(rt->dst.dev->features&NETIF_F_SG))
 884                                 alloclen = mtu;
 885                         else
 886                                 alloclen = fraglen;
 887
 888                         alloclen += exthdrlen;
 889
 890                         /* The last fragment gets additional space at tail.
 891                          * Note, with MSG_MORE we overallocate on fragments,
 892                          * because we have no idea what fragment will be
 893                          * the last.
 894                          */
 895                         if (datalen == length + fraggap)
 896                                 alloclen += rt->dst.trailer_len;
 897
 898                         if (transhdrlen) {
 899                                 skb = sock_alloc_send_skb(sk,
 900                                                 alloclen + hh_len + 15,
 901                                                 (flags & MSG_DONTWAIT), &err);
 902                         } else {
 903                                 skb = NULL;
 904                                 if (atomic_read(&sk->sk_wmem_alloc) <=
 905                                     2 * sk->sk_sndbuf)
 906                                         skb = sock_wmalloc(sk,
 907                                                            alloclen + hh_len + 15, 1,
 908                                                            sk->sk_allocation);
 909                                 if (unlikely(skb == NULL))
 910                                         err = -ENOBUFS;
 911                                 else
 912                                         /* only the initial fragment is
 913                                            time stamped */
 914                                         cork->tx_flags = 0;
 915                         }
 916                         if (skb == NULL)
 917                                 goto error;
 918
 919                         /*
 920                          *      Fill in the control structures
 921                          */
 922                         skb->ip_summed = csummode;
 923                         skb->csum = 0;
 924                         skb_reserve(skb, hh_len);
 925                         skb_shinfo(skb)->tx_flags = cork->tx_flags;
 926
 927                         /*
 928                          *      Find where to start putting bytes.
 929                          */
 930                         data = skb_put(skb, fraglen + exthdrlen);
 931                         skb_set_network_header(skb, exthdrlen);
 932                         skb->transport_header = (skb->network_header +
 933                                                  fragheaderlen);
 934                         data += fragheaderlen + exthdrlen;
 935
 936                         if (fraggap) {
 937                                 skb->csum = skb_copy_and_csum_bits(
 938                                         skb_prev, maxfraglen,
 939                                         data + transhdrlen, fraggap, 0);
 940                                 skb_prev->csum = csum_sub(skb_prev->csum,
 941                                                           skb->csum);
 942                                 data += fraggap;
 943                                 pskb_trim_unique(skb_prev, maxfraglen);
 944                         }
 945
 946                         copy = datalen - transhdrlen - fraggap;
 947                         if (copy > 0 && getfrag(from, data + transhdrlen, offset, copy, fraggap, skb) < 0) {
 948                                 err = -EFAULT;
 949                                 kfree_skb(skb);
 950                                 goto error;
 951                         }
 952
 953                         offset += copy;
 954                         length -= datalen - fraggap;
 955                         transhdrlen = 0;
 956                         exthdrlen = 0;
 957                         csummode = CHECKSUM_NONE;
 958
 959                         /*
 960                          * Put the packet on the pending queue.
 961                          */
 962                         __skb_queue_tail(queue, skb);
 963                         continue;
 964                 }
 965
 966                 if (copy > length)
 967                         copy = length;
 968
 969                 if (!(rt->dst.dev->features&NETIF_F_SG)) {
 970                         unsigned int off;
 971
 972                         off = skb->len;
 973                         if (getfrag(from, skb_put(skb, copy),
 974                                         offset, copy, off, skb) < 0) {
 975                                 __skb_trim(skb, off);
 976                                 err = -EFAULT;
 977                                 goto error;
 978                         }
 979                 } else {
 980                         int i = skb_shinfo(skb)->nr_frags;
 981                         skb_frag_t *frag = &skb_shinfo(skb)->frags[i-1];
 982                         struct page *page = cork->page;
 983                         int off = cork->off;
 984                         unsigned int left;
 985
 986                         if (page && (left = PAGE_SIZE - off) > 0) {
 987                                 if (copy >= left)
 988                                         copy = left;
 989                                 if (page != frag->page) {
 990                                         if (i == MAX_SKB_FRAGS) {
 991                                                 err = -EMSGSIZE;
 992                                                 goto error;
 993                                         }
 994                                         get_page(page);
 995                                         skb_fill_page_desc(skb, i, page, off, 0);
 996                                         frag = &skb_shinfo(skb)->frags[i];
 997                                 }
 998                         } else if (i < MAX_SKB_FRAGS) {
 999                                 if (copy > PAGE_SIZE)
1000                                         copy = PAGE_SIZE;
1001                                 page = alloc_pages(sk->sk_allocation, 0);
1002                                 if (page == NULL)  {
1003                                         err = -ENOMEM;
1004                                         goto error;
1005                                 }
1006                                 cork->page = page;
1007                                 cork->off = 0;
1008
1009                                 skb_fill_page_desc(skb, i, page, 0, 0);
1010                                 frag = &skb_shinfo(skb)->frags[i];
1011                         } else {
1012                                 err = -EMSGSIZE;
1013                                 goto error;
1014                         }
1015                         if (getfrag(from, page_address(frag->page)+frag->page_offset+frag->size, offset, copy, skb->len, skb) < 0) {
1016                                 err = -EFAULT;
1017                                 goto error;
1018                         }
1019                         cork->off += copy;
1020                         frag->size += copy;
1021                         skb->len += copy;
1022                         skb->data_len += copy;
1023                         skb->truesize += copy;
1024                         atomic_add(copy, &sk->sk_wmem_alloc);
1025                 }
1026                 offset += copy;
1027                 length -= copy;
1028         }
1029
1030         return 0;
1031
1032 error:
1033         cork->length -= length;
1034         IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTDISCARDS);
1035         return err;
1036 }
1037
1038 static int ip_setup_cork(struct sock *sk, struct inet_cork *cork,
1039                          struct ipcm_cookie *ipc, struct rtable **rtp)
1040 {
1041         struct inet_sock *inet = inet_sk(sk);
1042         struct ip_options_rcu *opt;
1043         struct rtable *rt;
1044
1045         /*
1046          * setup for corking.
1047          */
1048         opt = ipc->opt;
1049         if (opt) {
1050                 if (cork->opt == NULL) {
1051                         cork->opt = kmalloc(sizeof(struct ip_options) + 40,
1052                                             sk->sk_allocation);
1053                         if (unlikely(cork->opt == NULL))
1054                                 return -ENOBUFS;
1055                 }
1056                 memcpy(cork->opt, &opt->opt, sizeof(struct ip_options) + opt->opt.optlen);
1057                 cork->flags |= IPCORK_OPT;
1058                 cork->addr = ipc->addr;
1059         }
1060         rt = *rtp;
1061         if (unlikely(!rt))
1062                 return -EFAULT;
1063         /*
1064          * We steal reference to this route, caller should not release it
1065          */
1066         *rtp = NULL;
1067         cork->fragsize = inet->pmtudisc == IP_PMTUDISC_PROBE ?
1068                          rt->dst.dev->mtu : dst_mtu(&rt->dst);
1069         cork->dst = &rt->dst;
1070         cork->length = 0;
1071         cork->tx_flags = ipc->tx_flags;
1072         cork->page = NULL;
1073         cork->off = 0;
1074
1075         return 0;
1076 }
1077
1078 /*
1079  *      ip_append_data() and ip_append_page() can make one large IP datagram
1080  *      from many pieces of data. Each pieces will be holded on the socket
1081  *      until ip_push_pending_frames() is called. Each piece can be a page
1082  *      or non-page data.
1083  *
1084  *      Not only UDP, other transport protocols - e.g. raw sockets - can use
1085  *      this interface potentially.
1086  *
1087  *      LATER: length must be adjusted by pad at tail, when it is required.
1088  */
1089 int ip_append_data(struct sock *sk, struct flowi4 *fl4,
1090                    int getfrag(void *from, char *to, int offset, int len,
1091                                int odd, struct sk_buff *skb),
1092                    void *from, int length, int transhdrlen,
1093                    struct ipcm_cookie *ipc, struct rtable **rtp,
1094                    unsigned int flags)
1095 {
1096         struct inet_sock *inet = inet_sk(sk);
1097         int err;
1098
1099         if (flags&MSG_PROBE)
1100                 return 0;
1101
1102         if (skb_queue_empty(&sk->sk_write_queue)) {
1103                 err = ip_setup_cork(sk, &inet->cork.base, ipc, rtp);
1104                 if (err)
1105                         return err;
1106         } else {
1107                 transhdrlen = 0;
1108         }
1109
1110         return __ip_append_data(sk, fl4, &sk->sk_write_queue, &inet->cork.base, getfrag,
1111                                 from, length, transhdrlen, flags);
1112 }
1113
1114 ssize_t ip_append_page(struct sock *sk, struct flowi4 *fl4, struct page *page,
1115                        int offset, size_t size, int flags)
1116 {
1117         struct inet_sock *inet = inet_sk(sk);
1118         struct sk_buff *skb;
1119         struct rtable *rt;
1120         struct ip_options *opt = NULL;
1121         struct inet_cork *cork;
1122         int hh_len;
1123         int mtu;
1124         int len;
1125         int err;
1126         unsigned int maxfraglen, fragheaderlen, fraggap;
1127
1128         if (inet->hdrincl)
1129                 return -EPERM;
1130
1131         if (flags&MSG_PROBE)
1132                 return 0;
1133
1134         if (skb_queue_empty(&sk->sk_write_queue))
1135                 return -EINVAL;
1136
1137         cork = &inet->cork.base;
1138         rt = (struct rtable *)cork->dst;
1139         if (cork->flags & IPCORK_OPT)
1140                 opt = cork->opt;
1141
1142         if (!(rt->dst.dev->features&NETIF_F_SG))
1143                 return -EOPNOTSUPP;
1144
1145         hh_len = LL_RESERVED_SPACE(rt->dst.dev);
1146         mtu = cork->fragsize;
1147
1148         fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0);
1149         maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen;
1150
1151         if (cork->length + size > 0xFFFF - fragheaderlen) {
1152                 ip_local_error(sk, EMSGSIZE, fl4->daddr, inet->inet_dport, mtu);
1153                 return -EMSGSIZE;
1154         }
1155
1156         if ((skb = skb_peek_tail(&sk->sk_write_queue)) == NULL)
1157                 return -EINVAL;
1158
1159         cork->length += size;
1160         if ((size + skb->len > mtu) &&
1161             (sk->sk_protocol == IPPROTO_UDP) &&
1162             (rt->dst.dev->features & NETIF_F_UFO)) {
1163                 skb_shinfo(skb)->gso_size = mtu - fragheaderlen;
1164                 skb_shinfo(skb)->gso_type = SKB_GSO_UDP;
1165         }
1166
1167
1168         while (size > 0) {
1169                 int i;
1170
1171                 if (skb_is_gso(skb))
1172                         len = size;
1173                 else {
1174
1175                         /* Check if the remaining data fits into current packet. */
1176                         len = mtu - skb->len;
1177                         if (len < size)
1178                                 len = maxfraglen - skb->len;
1179                 }
1180                 if (len <= 0) {
1181                         struct sk_buff *skb_prev;
1182                         int alloclen;
1183
1184                         skb_prev = skb;
1185                         fraggap = skb_prev->len - maxfraglen;
1186
1187                         alloclen = fragheaderlen + hh_len + fraggap + 15;
1188                         skb = sock_wmalloc(sk, alloclen, 1, sk->sk_allocation);
1189                         if (unlikely(!skb)) {
1190                                 err = -ENOBUFS;
1191                                 goto error;
1192                         }
1193
1194                         /*
1195                          *      Fill in the control structures
1196                          */
1197                         skb->ip_summed = CHECKSUM_NONE;
1198                         skb->csum = 0;
1199                         skb_reserve(skb, hh_len);
1200
1201                         /*
1202                          *      Find where to start putting bytes.
1203                          */
1204                         skb_put(skb, fragheaderlen + fraggap);
1205                         skb_reset_network_header(skb);
1206                         skb->transport_header = (skb->network_header +
1207                                                  fragheaderlen);
1208                         if (fraggap) {
1209                                 skb->csum = skb_copy_and_csum_bits(skb_prev,
1210                                                                    maxfraglen,
1211                                                     skb_transport_header(skb),
1212                                                                    fraggap, 0);
1213                                 skb_prev->csum = csum_sub(skb_prev->csum,
1214                                                           skb->csum);
1215                                 pskb_trim_unique(skb_prev, maxfraglen);
1216                         }
1217
1218                         /*
1219                          * Put the packet on the pending queue.
1220                          */
1221                         __skb_queue_tail(&sk->sk_write_queue, skb);
1222                         continue;
1223                 }
1224
1225                 i = skb_shinfo(skb)->nr_frags;
1226                 if (len > size)
1227                         len = size;
1228                 if (skb_can_coalesce(skb, i, page, offset)) {
1229                         skb_shinfo(skb)->frags[i-1].size += len;
1230                 } else if (i < MAX_SKB_FRAGS) {
1231                         get_page(page);
1232                         skb_fill_page_desc(skb, i, page, offset, len);
1233                 } else {
1234                         err = -EMSGSIZE;
1235                         goto error;
1236                 }
1237
1238                 if (skb->ip_summed == CHECKSUM_NONE) {
1239                         __wsum csum;
1240                         csum = csum_page(page, offset, len);
1241                         skb->csum = csum_block_add(skb->csum, csum, skb->len);
1242                 }
1243
1244                 skb->len += len;
1245                 skb->data_len += len;
1246                 skb->truesize += len;
1247                 atomic_add(len, &sk->sk_wmem_alloc);
1248                 offset += len;
1249                 size -= len;
1250         }
1251         return 0;
1252
1253 error:
1254         cork->length -= size;
1255         IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTDISCARDS);
1256         return err;
1257 }
1258
1259 static void ip_cork_release(struct inet_cork *cork)
1260 {
1261         cork->flags &= ~IPCORK_OPT;
1262         kfree(cork->opt);
1263         cork->opt = NULL;
1264         dst_release(cork->dst);
1265         cork->dst = NULL;
1266 }
1267
1268 /*
1269  *      Combined all pending IP fragments on the socket as one IP datagram
1270  *      and push them out.
1271  */
1272 struct sk_buff *__ip_make_skb(struct sock *sk,
1273                               struct flowi4 *fl4,
1274                               struct sk_buff_head *queue,
1275                               struct inet_cork *cork)
1276 {
1277         struct sk_buff *skb, *tmp_skb;
1278         struct sk_buff **tail_skb;
1279         struct inet_sock *inet = inet_sk(sk);
1280         struct net *net = sock_net(sk);
1281         struct ip_options *opt = NULL;
1282         struct rtable *rt = (struct rtable *)cork->dst;
1283         struct iphdr *iph;
1284         __be16 df = 0;
1285         __u8 ttl;
1286
1287         if ((skb = __skb_dequeue(queue)) == NULL)
1288                 goto out;
1289         tail_skb = &(skb_shinfo(skb)->frag_list);
1290
1291         /* move skb->data to ip header from ext header */
1292         if (skb->data < skb_network_header(skb))
1293                 __skb_pull(skb, skb_network_offset(skb));
1294         while ((tmp_skb = __skb_dequeue(queue)) != NULL) {
1295                 __skb_pull(tmp_skb, skb_network_header_len(skb));
1296                 *tail_skb = tmp_skb;
1297                 tail_skb = &(tmp_skb->next);
1298                 skb->len += tmp_skb->len;
1299                 skb->data_len += tmp_skb->len;
1300                 skb->truesize += tmp_skb->truesize;
1301                 tmp_skb->destructor = NULL;
1302                 tmp_skb->sk = NULL;
1303         }
1304
1305         /* Unless user demanded real pmtu discovery (IP_PMTUDISC_DO), we allow
1306          * to fragment the frame generated here. No matter, what transforms
1307          * how transforms change size of the packet, it will come out.
1308          */
1309         if (inet->pmtudisc < IP_PMTUDISC_DO)
1310                 skb->local_df = 1;
1311
1312         /* DF bit is set when we want to see DF on outgoing frames.
1313          * If local_df is set too, we still allow to fragment this frame
1314          * locally. */
1315         if (inet->pmtudisc >= IP_PMTUDISC_DO ||
1316             (skb->len <= dst_mtu(&rt->dst) &&
1317              ip_dont_fragment(sk, &rt->dst)))
1318                 df = htons(IP_DF);
1319
1320         if (cork->flags & IPCORK_OPT)
1321                 opt = cork->opt;
1322
1323         if (rt->rt_type == RTN_MULTICAST)
1324                 ttl = inet->mc_ttl;
1325         else
1326                 ttl = ip_select_ttl(inet, &rt->dst);
1327
1328         iph = (struct iphdr *)skb->data;
1329         iph->version = 4;
1330         iph->ihl = 5;
1331         iph->tos = inet->tos;
1332         iph->frag_off = df;
1333         ip_select_ident(iph, &rt->dst, sk);
1334         iph->ttl = ttl;
1335         iph->protocol = sk->sk_protocol;
1336         iph->saddr = fl4->saddr;
1337         iph->daddr = fl4->daddr;
1338
1339         if (opt) {
1340                 iph->ihl += opt->optlen>>2;
1341                 ip_options_build(skb, opt, cork->addr, rt, 0);
1342         }
1343
1344         skb->priority = sk->sk_priority;
1345         skb->mark = sk->sk_mark;
1346         /*
1347          * Steal rt from cork.dst to avoid a pair of atomic_inc/atomic_dec
1348          * on dst refcount
1349          */
1350         cork->dst = NULL;
1351         skb_dst_set(skb, &rt->dst);
1352
1353         if (iph->protocol == IPPROTO_ICMP)
1354                 icmp_out_count(net, ((struct icmphdr *)
1355                         skb_transport_header(skb))->type);
1356
1357         ip_cork_release(cork);
1358 out:
1359         return skb;
1360 }
1361
1362 int ip_send_skb(struct sk_buff *skb)
1363 {
1364         struct net *net = sock_net(skb->sk);
1365         int err;
1366
1367         err = ip_local_out(skb);
1368         if (err) {
1369                 if (err > 0)
1370                         err = net_xmit_errno(err);
1371                 if (err)
1372                         IP_INC_STATS(net, IPSTATS_MIB_OUTDISCARDS);
1373         }
1374
1375         return err;
1376 }
1377
1378 int ip_push_pending_frames(struct sock *sk, struct flowi4 *fl4)
1379 {
1380         struct sk_buff *skb;
1381
1382         skb = ip_finish_skb(sk, fl4);
1383         if (!skb)
1384                 return 0;
1385
1386         /* Netfilter gets whole the not fragmented skb. */
1387         return ip_send_skb(skb);
1388 }
1389
1390 /*
1391  *      Throw away all pending data on the socket.
1392  */
1393 static void __ip_flush_pending_frames(struct sock *sk,
1394                                       struct sk_buff_head *queue,
1395                                       struct inet_cork *cork)
1396 {
1397         struct sk_buff *skb;
1398
1399         while ((skb = __skb_dequeue_tail(queue)) != NULL)
1400                 kfree_skb(skb);
1401
1402         ip_cork_release(cork);
1403 }
1404
1405 void ip_flush_pending_frames(struct sock *sk)
1406 {
1407         __ip_flush_pending_frames(sk, &sk->sk_write_queue, &inet_sk(sk)->cork.base);
1408 }
1409
1410 struct sk_buff *ip_make_skb(struct sock *sk,
1411                             struct flowi4 *fl4,
1412                             int getfrag(void *from, char *to, int offset,
1413                                         int len, int odd, struct sk_buff *skb),
1414                             void *from, int length, int transhdrlen,
1415                             struct ipcm_cookie *ipc, struct rtable **rtp,
1416                             unsigned int flags)
1417 {
1418         struct inet_cork cork;
1419         struct sk_buff_head queue;
1420         int err;
1421
1422         if (flags & MSG_PROBE)
1423                 return NULL;
1424
1425         __skb_queue_head_init(&queue);
1426
1427         cork.flags = 0;
1428         cork.addr = 0;
1429         cork.opt = NULL;
1430         err = ip_setup_cork(sk, &cork, ipc, rtp);
1431         if (err)
1432                 return ERR_PTR(err);
1433
1434         err = __ip_append_data(sk, fl4, &queue, &cork, getfrag,
1435                                from, length, transhdrlen, flags);
1436         if (err) {
1437                 __ip_flush_pending_frames(sk, &queue, &cork);
1438                 return ERR_PTR(err);
1439         }
1440
1441         return __ip_make_skb(sk, fl4, &queue, &cork);
1442 }
1443
1444 /*
1445  *      Fetch data from kernel space and fill in checksum if needed.
1446  */
1447 static int ip_reply_glue_bits(void *dptr, char *to, int offset,
1448                               int len, int odd, struct sk_buff *skb)
1449 {
1450         __wsum csum;
1451
1452         csum = csum_partial_copy_nocheck(dptr+offset, to, len, 0);
1453         skb->csum = csum_block_add(skb->csum, csum, odd);
1454         return 0;
1455 }
1456
1457 /*
1458  *      Generic function to send a packet as reply to another packet.
1459  *      Used to send TCP resets so far. ICMP should use this function too.
1460  *
1461  *      Should run single threaded per socket because it uses the sock
1462  *      structure to pass arguments.
1463  */
1464 void ip_send_reply(struct sock *sk, struct sk_buff *skb, __be32 daddr,
1465                    struct ip_reply_arg *arg, unsigned int len)
1466 {
1467         struct inet_sock *inet = inet_sk(sk);
1468         struct ip_options_data replyopts;
1469         struct ipcm_cookie ipc;
1470         struct flowi4 fl4;
1471         struct rtable *rt = skb_rtable(skb);
1472
1473         if (ip_options_echo(&replyopts.opt.opt, skb))
1474                 return;
1475
1476         ipc.addr = daddr;
1477         ipc.opt = NULL;
1478         ipc.tx_flags = 0;
1479
1480         if (replyopts.opt.opt.optlen) {
1481                 ipc.opt = &replyopts.opt;
1482
1483                 if (replyopts.opt.opt.srr)
1484                         daddr = replyopts.opt.opt.faddr;
1485         }
1486
1487         flowi4_init_output(&fl4, arg->bound_dev_if, 0,
1488                            RT_TOS(ip_hdr(skb)->tos),
1489                            RT_SCOPE_UNIVERSE, sk->sk_protocol,
1490                            ip_reply_arg_flowi_flags(arg),
1491                            daddr, rt->rt_spec_dst,
1492                            tcp_hdr(skb)->source, tcp_hdr(skb)->dest);
1493         security_skb_classify_flow(skb, flowi4_to_flowi(&fl4));
1494         rt = ip_route_output_key(sock_net(sk), &fl4);
1495         if (IS_ERR(rt))
1496                 return;
1497
1498         /* And let IP do all the hard work.
1499
1500            This chunk is not reenterable, hence spinlock.
1501            Note that it uses the fact, that this function is called
1502            with locally disabled BH and that sk cannot be already spinlocked.
1503          */
1504         bh_lock_sock(sk);
1505         inet->tos = ip_hdr(skb)->tos;
1506         sk->sk_priority = skb->priority;
1507         sk->sk_protocol = ip_hdr(skb)->protocol;
1508         sk->sk_bound_dev_if = arg->bound_dev_if;
1509         ip_append_data(sk, &fl4, ip_reply_glue_bits, arg->iov->iov_base, len, 0,
1510                        &ipc, &rt, MSG_DONTWAIT);
1511         if ((skb = skb_peek(&sk->sk_write_queue)) != NULL) {
1512                 if (arg->csumoffset >= 0)
1513                         *((__sum16 *)skb_transport_header(skb) +
1514                           arg->csumoffset) = csum_fold(csum_add(skb->csum,
1515                                                                 arg->csum));
1516                 skb->ip_summed = CHECKSUM_NONE;
1517                 ip_push_pending_frames(sk, &fl4);
1518         }
1519
1520         bh_unlock_sock(sk);
1521
1522         ip_rt_put(rt);
1523 }
1524
1525 void __init ip_init(void)
1526 {
1527         ip_rt_init();
1528         inet_initpeers();
1529
1530 #if defined(CONFIG_IP_MULTICAST) && defined(CONFIG_PROC_FS)
1531         igmp_mc_proc_init();
1532 #endif
1533 }